For the development sections:
[REQ] = Make a request to developers. Only to be used when already working on something and in need of help.
[WIP] = Work In Progress. Thread about something that is being worked on by you or someone else.
[DIS] = Discussion topic, to discuss anything that is related to game development.
[CPT] = Concept. An initial concept or idea that you want to propose.
[BUG] = To report a bug (report in the appropriate development section).